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42 pages, 1252 KiB  
Article
Antibody Titer Testing in Dogs: Evaluation of Three Point-of-Care Tests for Canine Core Vaccine Antigens Compared to Virus Neutralization
by Lena Janowitz, Ahmed Abd El Wahed, Uwe Truyen, Regina Hofmann-Lehmann and Andrea Monika Spiri
Vet. Sci. 2025, 12(8), 737; https://doi.org/10.3390/vetsci12080737 - 6 Aug 2025
Abstract
Antibody titer testing can be useful in controlling successful puppy immunization and can reduce unnecessary vaccinations in adult dogs. We evaluated three commercially available point-of-care tests (POCTs) for detecting antibodies against canine parvovirus (CPV-2), canine distemper virus (CDV) and canine adenovirus (CAV-1 and/or [...] Read more.
Antibody titer testing can be useful in controlling successful puppy immunization and can reduce unnecessary vaccinations in adult dogs. We evaluated three commercially available point-of-care tests (POCTs) for detecting antibodies against canine parvovirus (CPV-2), canine distemper virus (CDV) and canine adenovirus (CAV-1 and/or -2), comparing them to the reference virus neutralization (VN) assay. Sera from 200 client-owned dogs (13 healthy, 63 chronically diseased, 124 acute) and 60 specific pathogen-free (SPF) dogs, including 20 sera with maternally derived antibodies (MDA), were tested. All three POCTs demonstrated high sensitivity (79.0–100%) and specificity (97.8–100%) for CPV-2. In contrast, specificity for CDV and CAV was lower with POCT-1 (43.5% and 55.3%) and POCT-2 (42.4% and 79.2%), despite high sensitivity (CDV in both POCTs 98.7%; CAV POCT-1: 99.4%, POCT-2: 90.8%). POCT-3, by comparison, showed high specificity (CDV: 94.1%; CAV: 84.4%) but very low sensitivity (CDV: 17.4%; CAV: 33.1%). Only POCT-1 for CPV-2 detected MDA reliably, whereas the other two POCTs, and POCT-1 for CDV and CAV, did not. When compared to VN, the agreement in vaccination recommendations was 82% for POCT-1 and POCT-2, and 62% for POCT-3. In conclusion, all three POCTs reliably detected antibodies against CPV-2, including MDA with POCT-1. However, the lower specificity for CDV and CAV antibody detection in POCT-1 and POCT-2 raises concerns about misclassifying unprotected dogs as immune, while false-negatives with POCT-3 could lead to unnecessary vaccinations. Further optimization of all three POCTs for CDV and CAV is recommended. Full article
(This article belongs to the Special Issue Advances in Veterinary Clinical Microbiology)
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18 pages, 1472 KiB  
Article
Single-Dose Intranasal or Intramuscular Administration of Simian Adenovirus-Based H1N1 Vaccine Induces a Robust Humoral Response and Complete Protection in Mice
by Daria V. Voronina, Irina V. Vavilova, Olga V. Zubkova, Tatiana A. Ozharovskaia, Olga Popova, Anastasia S. Chugunova, Polina P. Goldovskaya, Denis I. Zrelkin, Daria M. Savina, Irina A. Favorskaya, Dmitry V. Shcheblyakov, Denis Y. Logunov and Alexandr L. Gintsburg
Viruses 2025, 17(8), 1085; https://doi.org/10.3390/v17081085 - 5 Aug 2025
Abstract
Despite the widespread accessibility of vaccines and antivirals, seasonal influenza virus epidemics continue to pose a threat to public health. In this study, we constructed a recombinant replication-deficient simian adenovirus type 25 vector carrying the full-length hemagglutinin (HA) of the H1N1 influenza virus, [...] Read more.
Despite the widespread accessibility of vaccines and antivirals, seasonal influenza virus epidemics continue to pose a threat to public health. In this study, we constructed a recombinant replication-deficient simian adenovirus type 25 vector carrying the full-length hemagglutinin (HA) of the H1N1 influenza virus, named rSAd25-H1. Both systemic and mucosal humoral immune responses, as well as the protective efficacy, were assessed in mice immunized via the intramuscular (IM) or intranasal (IN) route. A single-dose IM or IN administration of rSAd25-H1 elicited a robust systemic IgG antibody response, including hemagglutination inhibition antibodies. As expected, only IN immunization was able to induce IgA production in serum and respiratory mucosa. Notably, a single dose of rSAd25-H1 at the highest dose (1010 viral particles) conferred complete protection against lethal homologous H1N1 challenge in mice despite the route of administration. These findings demonstrate the potential of simian adenovirus type 25-based vectors as a promising candidate for intranasal vaccine development targeting respiratory pathogens. Full article
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16 pages, 1921 KiB  
Article
A Bivalent mRNA Vaccine Efficiently Prevents Gammaherpesvirus Latent Infection
by Yannan Yin, Jinkai Zang, Huichun Shi, Zhuang Wang, Linlin Kuang, Shuxia Wang, Haikun Wang, Ning Li, Xiaozhen Liang and Zhong Huang
Vaccines 2025, 13(8), 830; https://doi.org/10.3390/vaccines13080830 - 4 Aug 2025
Viewed by 170
Abstract
Background: It is still challenging to develop effective vaccines against tumorigenic human gammaherpesviruses such as Epstein–Barr virus (EBV). A major obstacle is the lack of a small animal model that reproduces the natural infection course of human gammaherpesviruses to allow for proper [...] Read more.
Background: It is still challenging to develop effective vaccines against tumorigenic human gammaherpesviruses such as Epstein–Barr virus (EBV). A major obstacle is the lack of a small animal model that reproduces the natural infection course of human gammaherpesviruses to allow for proper assessment of vaccine efficacy. Murine gammaherpesvirus 68 (MHV68) is a natural pathogen of wild rodents and laboratory mice and therefore can be used as a surrogate for human gammaherpesviruses to evaluate vaccination strategies. Methods: In this study, two mRNA vaccine candidates were generated, one encoding a fusion protein of the MHV68 gH with the gL (gHgL-mRNA) and the other expressing the MHV68 gB protein (gB-mRNA). The immunogenicity and protective efficacy of the mRNA vaccine candidates were evaluated in a mouse model of MHV68 infection. Results: The gHgL-mRNA but not the gB-mRNA candidate vaccine was able to induce neutralizing antibodies in mice, whereas both vaccines could elicit antigen-specific T-cell responses. Following MHV68 intranasal inoculation, complete blocking of the establishment of viral latency was observed in some mice immunized with individual gHgL-mRNA or gB-mRNA vaccines. Notably, co-immunization with the two mRNA vaccines appeared to be more effective than individual vaccines, achieving sterile immunity in 50% of the vaccinated mice. Conclusions: This study demonstrates that immunization with mRNA platform-based subunit vaccines is indeed capable of preventing MHV68 latent infection, thus validating a safe and efficacious vaccination strategy that may be applicable to human gammaherpesviruses. Full article
(This article belongs to the Special Issue The Development of mRNA Vaccines)
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17 pages, 2225 KiB  
Article
The Persistence of Cross-Reactive Immunity to Influenza B/Yamagata Neuraminidase Despite the Disappearance of the Lineage: Structural and Serological Evidence
by Yulia Desheva, Polina Kudar, Maria Sergeeva, Pei-Fong Wong, Tamara Shvedova, Ekaterina Bazhenova, Evelyna Krylova, Maria Kurpiaeva, Ekaterina Romanovskaya-Romanko, Vera Krivitskaya, Kira Kudria, Irina Isakova-Sivak and Marina Stukova
Int. J. Mol. Sci. 2025, 26(15), 7476; https://doi.org/10.3390/ijms26157476 - 2 Aug 2025
Viewed by 224
Abstract
Influenza B viruses, divided into B/Victoria and B/Yamagata lineages, have not had B/Yamagata isolates after 2020. A study evaluated immunity to influenza B surface antigens hemagglutinin (HA) and neuraminidase (NA) in 138 patient sera from 2023 and 23 pairs of sera from 2018 [...] Read more.
Influenza B viruses, divided into B/Victoria and B/Yamagata lineages, have not had B/Yamagata isolates after 2020. A study evaluated immunity to influenza B surface antigens hemagglutinin (HA) and neuraminidase (NA) in 138 patient sera from 2023 and 23 pairs of sera from 2018 to 2019 vaccine recipients. The phylogenetic tree of the influenza B virus, based on HA and NA genes, shows that the Yamagata lineage evolves gradually, while the Victoria lineage exhibits rapid mutations with short branches. In 2023, mean levels of antibodies to HA and NA of B/Yamagata virus were higher than to B/Victoria, despite no cases of B/Yamagata lineage isolation after 2020. The titers of antibodies to NA of B/Yamagata statistically significantly differed among individuals born before and after 1988. Among patients examined in 2018–2019, neuraminidase-inhibiting (NI) antibody titers before vaccination were higher to B/Yamagata than to B/Victoria, and NI antibodies to B/Victoria and B/Yamagata positively correlated with neutralizing antibodies to B/Victoria virus before and after vaccination. Immunity to B/Yamagata virus was stronger in 2023, despite no isolation since 2020, probably due to the presence of cross-reactive antibodies from B/Victoria infections or vaccinations. Antibodies to NA of B/Victoria and B/Yamagata in 2023 correlated significantly in patients born before 1988, potentially supporting the concept of ‘antigenic sin’ phenomenon for influenza B viruses. The fact that NI antibody titers to B/Victoria and B/Yamagata correlated with neutralizing antibody titers to B/Victoria may suggest broad cross-protection. Studying influenza B virus NA antigenic properties helps understand the evolution and antigenic competition of HA and NA. Full article
(This article belongs to the Special Issue Respiratory Virus Infection)
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27 pages, 2147 KiB  
Systematic Review
Immunogenicity, Safety, and Protective Efficacy of Mucosal Vaccines Against Respiratory Infectious Diseases: A Systematic Review and Meta-Analysis
by Jiaqi Chen, Weitong Lin, Chaokai Yang, Wenqi Lin, Xinghui Cheng, Haoyuan He, Xinhua Li and Jingyou Yu
Vaccines 2025, 13(8), 825; https://doi.org/10.3390/vaccines13080825 - 31 Jul 2025
Viewed by 303
Abstract
Background/Objectives: Mucosal vaccines, delivered intranasally or via inhalation, are being studied for respiratory infectious diseases like COVID-19 and influenza. These vaccines aim to provide non-invasive administration and strong immune responses at infection sites, making them a promising area of research. This systematic review [...] Read more.
Background/Objectives: Mucosal vaccines, delivered intranasally or via inhalation, are being studied for respiratory infectious diseases like COVID-19 and influenza. These vaccines aim to provide non-invasive administration and strong immune responses at infection sites, making them a promising area of research. This systematic review and meta-analysis assessed their immunogenicity, safety, and protective efficacy. Methods: The study design was a systematic review and meta-analysis, searching PubMed and Cochrane databases up to 30 May 2025. Inclusion criteria followed the PICOS framework, focusing on mucosal vaccines for COVID-19, influenza, RSV, pertussis, and tuberculosis. Results: A total of 65 studies with 229,614 participants were included in the final analysis. Mucosal COVID-19 vaccines elicited higher neutralizing antibodies compared to intramuscular vaccines (SMD = 2.48, 95% CI: 2.17–2.78 for wild-type; SMD = 1.95, 95% CI: 1.32–2.58 for Omicron), with varying efficacy by route (inhaled VE = 47%, 95% CI: 22–74%; intranasal vaccine VE = 17%, 95% CI: 0–31%). Mucosal influenza vaccines protected children well (VE = 62%, 95% CI: 30–46%, I2 = 17.1%), but seroconversion rates were lower than those of intramuscular vaccines. RSV and pertussis vaccines had high seroconversion rates (73% and 52%, respectively). Tuberculosis vaccines were reviewed systemically, exhibiting robust cellular immunogenicity. Safety was comparable to intramuscular vaccines or placebo, with no publication bias detected. Conclusions: Current evidence suggests mucosal vaccines are immunogenic, safe, and protective, particularly for respiratory diseases. This review provides insights for future research and vaccination strategies, though limitations include varying efficacy by route and study heterogeneity. Full article
(This article belongs to the Special Issue Immune Correlates of Protection in Vaccines, 2nd Edition)
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24 pages, 3039 KiB  
Article
Plasmodium falciparum Subtilisin-like Domain-Containing Protein (PfSDP), a Cross-Stage Antigen, Elicits Short-Lived Antibody Response Following Natural Infection with Plasmodium falciparum
by Jonas A. Kengne-Ouafo, Collins M. Morang’a, Nancy K. Nyakoe, Daniel Dosoo, Richmond Tackie, Joe K. Mutungi, Saikou Y. Bah, Lucas N. Amenga-Etego, Britta Urban, Gordon A. Awandare, Bismarck Dinko and Yaw Aniweh
Cells 2025, 14(15), 1184; https://doi.org/10.3390/cells14151184 - 31 Jul 2025
Viewed by 554
Abstract
With the increasing detection of artemisinin resistance to front-line antimalarials in Africa and notwithstanding the planned roll-out of RTS’S and R21 in Africa, the search for new vaccines with high efficacy remains an imperative. Towards this endeavour, we performed in silico screening to [...] Read more.
With the increasing detection of artemisinin resistance to front-line antimalarials in Africa and notwithstanding the planned roll-out of RTS’S and R21 in Africa, the search for new vaccines with high efficacy remains an imperative. Towards this endeavour, we performed in silico screening to identify Plasmodium falciparum gametocyte stage genes that could be targets of protection or diagnosis. Through the analysis we identified a gene, Pf3D7_1105800, coding for a Plasmodium falciparum subtilisin-like domain-containing protein (PfSDP) and thus dubbed the gene Pfsdp. Genetic diversity assessment revealed the Pfsdp gene to be relatively conserved across continents with signs of directional selection. Using RT qPCR and Western blots, we observed that Pfsdp is expressed in all developmental stages of the parasite both at the transcript and protein level. Immunofluorescence assays found PfSDP protein co-localizing with PfMSP-1 and partially with Pfs48/45 at the asexual and sexual stages, respectively. Further, we demonstrated that anti-PfSDP peptide-specific antibodies inhibited erythrocyte invasion by 20–60% in a dose-dependent manner, suggesting that PfSDP protein might play a role in merozoite invasion. We also discovered that PfSDP protein is immunogenic in children from different endemic areas with antibody levels increasing from acute infection to day 7 post-treatment, followed by a gradual decay. The limited effect of antibodies on erythrocyte invasion could imply that it might be more involved in other processes in the development of the parasite. Full article
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14 pages, 2882 KiB  
Article
Babesia bovis Enolase Is Expressed in Intracellular Merozoites and Contains B-Cell Epitopes That Induce Neutralizing Antibodies In Vitro
by Alma Cárdenas-Flores, Minerva Camacho-Nuez, Massaro W. Ueti, Mario Hidalgo-Ruiz, Angelina Rodríguez-Torres, Diego Josimar Hernández-Silva, José Guadalupe Gómez-Soto, Masahito Asada, Shin-ichiro Kawazu, Alma R. Tamayo-Sosa, Rocío Alejandra Ruiz-Manzano and Juan Mosqueda
Vaccines 2025, 13(8), 818; https://doi.org/10.3390/vaccines13080818 - 31 Jul 2025
Viewed by 229
Abstract
Background: Bovine babesiosis, caused by the tick-borne apicomplexan parasite Babesia spp., is an economically significant disease that threatens the cattle industry worldwide. Babesia bovis is the most pathogenic species, leading to high morbidity and mortality in infected animals. One promising approach to [...] Read more.
Background: Bovine babesiosis, caused by the tick-borne apicomplexan parasite Babesia spp., is an economically significant disease that threatens the cattle industry worldwide. Babesia bovis is the most pathogenic species, leading to high morbidity and mortality in infected animals. One promising approach to vaccination against bovine babesiosis involves the use of multiple protective antigens, offering advantages over traditional live-attenuated vaccines. Tools such as immunobioinformatics and reverse vaccinology have facilitated the identification of novel antigens. Enolase, a “moonlighting” enzyme of the glycolytic pathway with demonstrated vaccine potential in other pathogens, has not yet been studied in B. bovis. Methods: In this study, the enolase gene from two B. bovis isolates was successfully identified and sequenced. The gene, consisting of 1366 base pairs, encodes a predicted protein of 438 amino acids. Its expression in intraerythrocytic parasites was confirmed by RT-PCR. Two peptides containing predicted B-cell epitopes were synthesized and used to immunize rabbits. Hyperimmune sera were then analyzed by ELISA, confocal microscopy, Western blot, and an in vitro neutralization assay. Results: The hyperimmune sera showed high antibody titers, reaching up to 1:256,000. Specific antibodies recognized intraerythrocytic merozoites by confocal microscopy and bound to a ~47 kDa protein in erythrocytic cultures of B. bovis as detected by Western blot. In the neutralization assay, antibodies raised against peptide 1 had no observable effect, whereas those targeting peptide 2 significantly reduced parasitemia by 71.99%. Conclusions: These results suggest that B. bovis enolase contains B-cell epitopes capable of inducing neutralizing antibodies and may play a role in parasite–host interactions. Enolase is therefore a promising candidate for further exploration as a vaccine antigen. Nonetheless, additional experimental studies are needed to fully elucidate its biological function and validate its vaccine potential. Full article
(This article belongs to the Special Issue Vaccines against Arthropods and Arthropod-Borne Pathogens)
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11 pages, 666 KiB  
Article
Low Hepatitis B Immunity Among Ukrainian Refugee Children and Adolescents in Poland: Need for Targeted Screening and Vaccination
by Lidia Stopyra, Karolina Banach, Magdalena Wood, Justyna Stala and Anna Merklinger-Gruchała
Vaccines 2025, 13(8), 816; https://doi.org/10.3390/vaccines13080816 - 31 Jul 2025
Viewed by 284
Abstract
Background: The 2022 conflict in Ukraine triggered mass migration, leading to a significant influx of Ukrainian refugee children into Poland. This situation raises concerns about hepatitis B virus immunity, as Ukraine’s hepatitis B vaccination coverage has been inconsistent compared to Poland’s high vaccination [...] Read more.
Background: The 2022 conflict in Ukraine triggered mass migration, leading to a significant influx of Ukrainian refugee children into Poland. This situation raises concerns about hepatitis B virus immunity, as Ukraine’s hepatitis B vaccination coverage has been inconsistent compared to Poland’s high vaccination rates. Objective: To evaluate hepatitis B immunity and infection prevalence among Ukrainian refugee children residing in Southern Poland and to assess implications for vaccination strategies in the host country. Methods: A prospective cross-sectional study was conducted on 1322 Ukrainian refugee children (0–18 years) presenting to a pediatric infectious diseases department in Southern Poland between February 2022 and March 2024. Data on vaccination history, demographic characteristics, and selected laboratory parameters, including hepatitis B surface antigen and anti-HBs antibody levels, were collected. Protective immunity was defined as anti-HBs antibody levels ≥10 IU/L. Results: Among the participants (mean age 9.9 years; 50.2% female), 83.2% were reported as vaccinated according to national immunization programs, but only 64.9% demonstrated protective anti-HBs antibody levels. Protective antibody prevalence declined significantly with age, with less than half of adolescents aged 15–18 years showing immunity. Five children (0.4%) were diagnosed with chronic hepatitis B, four of whom were unvaccinated. Conclusions: This study identifies a significant gap in hepatitis B immunity among Ukrainian adolescent refugees residing in Southern Poland, with less than half possessing protective anti-HBs antibody levels. This immunity gap and the high risk of sexual transmission of the hepatitis B virus in adolescents highlight the urgent need for comprehensive surveillance, screening, and catch-up vaccination programs. Full article
(This article belongs to the Special Issue Vaccination, Public Health and Epidemiology)
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18 pages, 6852 KiB  
Article
A Novel Anti-BoNT/A Neutralizing Antibody Possessed Overlapped Epitope with SV2 and Had Prolonged Half-Life In Vivo
by Shangde Peng, Naijing Hu, Fenghao Peng, Huirong Mu, Zihan Yi, Cong Xing, Liang Zhang, Wen Hu, Xinyi Zhou, Yan Wen, Jiannan Feng and Chunxia Qiao
Toxins 2025, 17(8), 376; https://doi.org/10.3390/toxins17080376 - 29 Jul 2025
Viewed by 327
Abstract
The C-terminus of the BoNT/A heavy chain (BoNT/AHC) mediates binding to its receptor, SV2, a critical step for toxicity. Antibody inhibition of this interaction enhances neuronal survival. We previously identified a functional anti-BoNT/AHC nanobody, HM. To extend its in vivo half-life, we designed [...] Read more.
The C-terminus of the BoNT/A heavy chain (BoNT/AHC) mediates binding to its receptor, SV2, a critical step for toxicity. Antibody inhibition of this interaction enhances neuronal survival. We previously identified a functional anti-BoNT/AHC nanobody, HM. To extend its in vivo half-life, we designed and prepared two Fc-optimized nanoparticles, HM-Fc5 and HM-Fc6. Structural modeling (homology/docking) of the HM Fv-AHC complex predicted that HM engages key AHC residues (Tyr1155, Phe1160, Ile1161, Val1184, Asn1188, Lys1189, Glu1190), which overlap with the SV2 binding site. This suggests HM’s protective mechanism involves blocking toxin-receptor binding and cellular entry. HM-Fc5 and HM-Fc6 retained the stability and function of the parental HM antibody while exhibiting prolonged in vivo half-life. These optimized nanobodies offer economical candidates potentially enabling longer dosing intervals, beneficial for prophylaxis or chronic disease treatment. Significance Statement: The purpose of the study is to design and prepare two Fc optimized nanoparticles, HM-Fc5 and HM-Fc6, and predict the key residues involved in the interaction between HMs and AHC. The experimental results showed that HM-Fc5 and HM-Fc6 have the same stability as the parent HM antibody but have a longer half-life in vivo. The key residues Tyr1155, Phe1160, Ile1161, Val1184, Asn1188, Lys1189, and Glu1190 overlap with the SV2 binding site. Our experimental results indicate that these nanobody candidates are not only more economical and convenient, but may also have longer dosing intervals, providing strong evidence and reference for prolonging the in vivo half-life of nanomaterials. Full article
(This article belongs to the Section Bacterial Toxins)
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12 pages, 1307 KiB  
Article
Protection Against Transplacental Transmission of a Highly Virulent Classical Swine Fever Virus Two Weeks After Single-Dose FlagT4G Vaccination in Pregnant Sows
by Liani Coronado, Àlex Cobos, Adriana Muñoz-Aguilera, Sara Puente-Marin, Gemma Guevara, Cristina Riquelme, Saray Heredia, Manuel V. Borca and Llilianne Ganges
Vaccines 2025, 13(8), 803; https://doi.org/10.3390/vaccines13080803 - 28 Jul 2025
Viewed by 386
Abstract
Background/Objectives: Classical swine fever (CSF) continues to challenge global eradication efforts, particularly in endemic regions, where pregnant sows face heightened risks of vertical transmission following exposure to CSFV. Methods: This study evaluates the early protective efficacy of FlagT4G, a novel live attenuated DIVA-compatible [...] Read more.
Background/Objectives: Classical swine fever (CSF) continues to challenge global eradication efforts, particularly in endemic regions, where pregnant sows face heightened risks of vertical transmission following exposure to CSFV. Methods: This study evaluates the early protective efficacy of FlagT4G, a novel live attenuated DIVA-compatible vaccine. Pregnant sows were vaccinated at mid-gestation and challenged 14 days later with a highly virulent CSFV strain. Results: FlagT4G conferred complete clinical protection, preventing both maternal viremia and transplacental transmission. No CSFV RNA, specific antibodies, or IFN-α were detected in fetal samples from vaccinated animals. In contrast, unvaccinated sows exhibited clinical signs, high viral loads, and widespread fetal infection. Interestingly, early protection was observed even in the absence of strong humoral responses in some vaccinated sows, suggesting a potential role for innate or T-cell-mediated immunity in conferring rapid protection. Conclusions: The demonstrated efficacy of FlagT4G within two weeks of vaccination underscores its feasibility for integration into emergency vaccination programs. Its DIVA compatibility and ability to induce early fetal protection against highly virulent CSFV strains position it as a promising tool for CSF control and eradication strategies. Full article
(This article belongs to the Special Issue Vaccines for Porcine Viruses)
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16 pages, 2491 KiB  
Article
High-Yield Production of PCV2 Cap Protein: Baculovirus Vector Construction and Cultivation Process Optimization
by Long Cheng, Denglong Xie, Wei Ji, Xiaohong Ye, Fangheng Yu, Xiaohui Yang, Nan Gao, Yan Zhang, Shu Zhu and Yongqi Zhou
Vaccines 2025, 13(8), 801; https://doi.org/10.3390/vaccines13080801 - 28 Jul 2025
Viewed by 335
Abstract
Background/Objectives: Porcine circovirus type 2 (PCV2) infection causes porcine circovirus disease (PCVD), a global immunosuppressive disease in pigs. Its clinical manifestations include post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS), which cause significant economic losses to the swine industry. [...] Read more.
Background/Objectives: Porcine circovirus type 2 (PCV2) infection causes porcine circovirus disease (PCVD), a global immunosuppressive disease in pigs. Its clinical manifestations include post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS), which cause significant economic losses to the swine industry. The Cap protein, which is the major protective antigen of PCV2, can self-assemble to form virus-like particles (VLPs) in the insect baculovirus expression system. Few studies have compared the expression of Cap proteins in different baculovirus expression systems. Methods: In this study, we compared two commonly commercialized baculovirus construction systems with the Cap protein expression in various insect cells. Results: The results demonstrate that the flashBAC system expressed the Cap protein at higher levels than the Bac-to-Bac system. Notably, when expressing four copies of the Cap protein, the flashBAC system achieved the highest protein yield in High Five cells, where it reached 432 μg/mL at 5 days post-infection (dpi) with 27 °C cultivation. Animal experiments confirmed that the purified Cap protein effectively induced specific antibody production in mice and swine. Conclusions: This study provides critical data for optimizing the production of the PCV2 Cap protein, which is of great significance for reducing the production cost of PCV2 vaccines and improving the industrial production efficiency. Full article
(This article belongs to the Section Veterinary Vaccines)
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19 pages, 4424 KiB  
Article
Humoral and Memory B Cell Responses Following SARS-CoV-2 Infection and mRNA Vaccination
by Martina Bozhkova, Ralitsa Raycheva, Steliyan Petrov, Dobrina Dudova, Teodora Kalfova, Marianna Murdjeva, Hristo Taskov and Velizar Shivarov
Vaccines 2025, 13(8), 799; https://doi.org/10.3390/vaccines13080799 - 28 Jul 2025
Viewed by 374
Abstract
Background: Understanding the duration and quality of immune memory following SARS-CoV-2 infection and vaccination is critical for informing public health strategies and vaccine development. While waning antibody levels have raised concerns about long-term protection, the persistence of memory B cells (MBCs) and T [...] Read more.
Background: Understanding the duration and quality of immune memory following SARS-CoV-2 infection and vaccination is critical for informing public health strategies and vaccine development. While waning antibody levels have raised concerns about long-term protection, the persistence of memory B cells (MBCs) and T cells plays a vital role in sustaining immunity. Materials and Methods: We conducted a longitudinal prospective study over 12 months, enrolling 285 participants in total, either after natural infection or vaccination with BNT162b2 or mRNA-1273. Peripheral blood samples were collected at four defined time points (baseline, 1–2 months, 6–7 months, and 12–13 months after vaccination or disease onset). Immune responses were assessed through serological assays quantifying anti-RBD IgG and neutralizing antibodies, B-ELISPOT, and multiparameter flow cytometry for S1-specific memory B cells. Results: Both mRNA vaccines induced robust B cell and antibody responses, exceeding those observed after natural infection. Memory B cell frequencies peaked at 6 months and declined by 12 months, but remained above the baseline. The mRNA-1273 vaccine elicited stronger and more durable humoral and memory B-cell-mediated immunity compared to BNT162b2, likely influenced by its higher mRNA dose and longer prime-boost interval. Class-switched memory B cells and S1-specific B cells were significantly expanded in vaccine recipients. Natural infection induced more heterogeneous immune memory. Conclusions: Both mRNA vaccination and natural SARS-CoV-2 infection induce a comparable expansion of memory B cell subsets, reflecting a consistent pattern of humoral immune responses across all studied groups. These findings highlight the importance of vaccination in generating sustained immunological memory and suggest that the vaccine platform and dosage influence the magnitude and durability of immune responses against SARS-CoV-2. Full article
(This article belongs to the Special Issue Evaluating the Immune Response to RNA Vaccine)
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10 pages, 254 KiB  
Article
Lupus Anticoagulant Positivity as a Risk Marker for Hemolytic Anemia in Patients with APS
by Ji-Hyoun Kang
Medicina 2025, 61(8), 1364; https://doi.org/10.3390/medicina61081364 - 28 Jul 2025
Viewed by 314
Abstract
Background and Objectives: Thrombocytopenia and hemolytic anemia are common but non-criteria manifestations of antiphospholipid syndrome (APS). However, their relationship with specific immunological profiles remains poorly characterized. This study aimed to evaluate these hematologic manifestations and identify their serological associations in patients with [...] Read more.
Background and Objectives: Thrombocytopenia and hemolytic anemia are common but non-criteria manifestations of antiphospholipid syndrome (APS). However, their relationship with specific immunological profiles remains poorly characterized. This study aimed to evaluate these hematologic manifestations and identify their serological associations in patients with APS. Materials and Methods: We retrospectively reviewed 346 patients diagnosed with APS. Demographic, clinical, and laboratory characteristics were analyzed. Logistic regression was used to identify risk factors associated with hemolytic anemia. Results: The mean age was 47.1 ± 13.1 years, and 71.7% were female. Thrombocytopenia was present in 34.5%, and hemolytic anemia in 16.5% of patients. Lupus anticoagulant (LAC) was the most common antibody (66.8%). In univariate analysis, hemolytic anemia was significantly associated with LAC positivity (OR 4.216, 95% CI: 2.326–7.640, p < 0.001), anticardiolipin IgG (OR 7.170, p = 0.007), triple positivity (OR 3.638, p = 0.002), and diabetes mellitus (OR 2.084, p = 0.007). DIAPS showed a protective trend (OR 0.547, p = 0.002). In multivariate analysis, only LAC remained an independent risk factor for hemolytic anemia (adjusted OR 3.557, 95% CI: 1.355–9.335, p = 0.003). Conclusions: LAC positivity is an independent predictor of hemolytic anemia in APS. These findings suggest a distinct immunologic profile among patients with hematologic involvement and highlight the need for further investigation into non-criteria manifestations. Full article
(This article belongs to the Special Issue Autoimmune Diseases: Advances and Challenges)
16 pages, 2036 KiB  
Article
Adjuvanted Protein Vaccines Boost RNA-Based Vaccines for Broader and More Potent Immune Responses
by Jiho Kim, Jenn Davis, Bryan Berube, Malcolm Duthie, Sean A. Gray and Darrick Carter
Vaccines 2025, 13(8), 797; https://doi.org/10.3390/vaccines13080797 - 28 Jul 2025
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Abstract
Background/Objectives: mRNA vaccines introduced during the COVID-19 pandemic were a significant step forward in the rapid development and deployment of vaccines in a global pandemic context. These vaccines showed good protective efficacy, but—due to limited breadth of the immune response—they required frequent [...] Read more.
Background/Objectives: mRNA vaccines introduced during the COVID-19 pandemic were a significant step forward in the rapid development and deployment of vaccines in a global pandemic context. These vaccines showed good protective efficacy, but—due to limited breadth of the immune response—they required frequent boosters with manufactured spike sequences that often lagged behind the circulating strains. In order to enhance the breadth, durability, and magnitude of immune responses, we studied the effect of combining priming with an RNA vaccine technology with boosting with protein/adjuvant using a TLR4-agonist based adjuvant. Methods: Specifically, four proprietary adjuvants (EmT4TM, LiT4QTM, MiT4TM, and AlT4TM) were investigated in combination with multiple modes of SARS-CoV-2 vaccination (protein, peptide, RNA) for their effectiveness in boosting antibody responses to SARS-CoV-2 spike protein in murine models. Results: Results showed significant improvement in immune response strength and breadth—especially against more distant SARS-CoV-2 variants such as Omicron—when adjuvants were used in combination with boosters following an RNA vaccine prime. Conclusions: The use of novel TLR4 adjuvants in combination with protein or RNA vaccinations presents a promising strategy for improving the efficacy of vaccines in the event of future pandemics, by leveraging rapid response using an RNA vaccine prime and following up with protein/adjuvant-based vaccines to enhance the breadth of immunity. Full article
(This article belongs to the Special Issue Novel Adjuvants and Delivery Systems for Vaccines)
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Article
Evaluation of Poxvirus-Specific Antibody Response in Monkey Poxvirus-Negative and -Positive Cohorts
by Nannan Jia, Lin Ai, Yunping Ma, Chen Hua, Qi Shen, Chen Wang, Teng Li, Yingdan Wang, Yunyi Li, Yin Yang, Chi Zhou, Min Chen, Huanyu Wu, Xin Chen, Lu Lu, Yanqiu Zhou, Jinghe Huang and Fan Wu
Vaccines 2025, 13(8), 795; https://doi.org/10.3390/vaccines13080795 - 27 Jul 2025
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Abstract
Objectives: Understanding the antibody response in monkeypox virus (MPXV)-infected and uninfected individuals is essential for developing next-generation MPXV vaccines. This study aimed to characterize neutralizing antibody (NAb) and antibody-dependent cellular cytotoxicity (ADCC) responses in both groups, providing insights into immune protection and vaccine [...] Read more.
Objectives: Understanding the antibody response in monkeypox virus (MPXV)-infected and uninfected individuals is essential for developing next-generation MPXV vaccines. This study aimed to characterize neutralizing antibody (NAb) and antibody-dependent cellular cytotoxicity (ADCC) responses in both groups, providing insights into immune protection and vaccine design. Methods: A recombinant vaccinia Tian Tan (VTT) virus was utilized to develop high-throughput luciferase-reporter-based neutralization and ADCC assays. These assays were applied to evaluate the presence and levels of poxvirus-specific antibodies in MPXV-infected and uninfected individuals, including those vaccinated with vaccinia-based vaccines. Results: Poxvirus-specific NAbs were detected in MPXV-negative individuals with prior vaccinia vaccination. However, MSM individuals exhibited significantly lower pre-existing NAb levels than non-MSM individuals, potentially contributing to their higher susceptibility to MPXV infection. In individuals with mild MPXV infection, robust NAb and ADCC responses were observed, regardless of vaccination status. Additionally, HIV-positive individuals demonstrated comparable antibody responses following MPXV infection. Conclusions: These findings highlight the potential role of pre-existing NAbs in MPXV susceptibility and the strong immune response elicited by mild MPXV infection. Further research is needed to determine whether MPXV-specific antibodies mitigate disease progression, which could inform the development of effective MPXV vaccines. Full article
(This article belongs to the Section Human Papillomavirus Vaccines)
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